RNLI lifeguards were returning from Booby's Bay to Constantine, near Padstow in north Cornwall on Sunday, where they had been giving safety advice to swimmers in danger of being caught in a rip current, when their Mitsubishi L200 patrol vehicle became stuck in soft sand.

Despite their attempts to free the vehicle - something they are trained to do - the incoming tide claimed the truck before they could free it.

A crowd gathered as another patrol truck and then a local farmer with his tractor came to help, but they still couldn't get the truck out.

Christine Megson, from Exeter, who was among the watching crowd, told the Western Morning News: "A crowd formed on the cliff top - people were laughing. I would imagine there will be some very red faces."

Steve Instance, the RNLI lifeguard inspector, said an investigation into the incident had been launched.

"Unfortunately, with the tide quickly coming in, they were unable to free the vehicle in time and the tide subsequently came in over it," he said.

"The lifeguards, RNLI technical team and the local farmer, who is one of the locally nominated people who the charity pre-arrange assistance (with) in the event this should happen, attempted to recover the vehicle when the tide was next low enough, which was around 7pm. However after carrying out a risk assessment it became clear that the recovery would need to take place during daylight hours to maximise safety.

"The RNLI patrols over 160 beaches around the coast and in the last three months they have saved over 40 lives. When someone is in trouble in the sea, seconds count and lifeguards use patrol vehicles to enable them to reach people quickly and for the carriage of safety equipment. This is an isolated incident which highlights the power of the sea and reminds us of the need to take care at the beach.

"The patrol vehicle has now been recovered. Thankfully on this occasion no one was hurt, however there will be a full investigation into the incident and any lessons to be learnt will be incorporated into the 4x4 training the lifeguards receive."